Gellan gum, also known as S-60, is a bacterial heteropolysaccharide produced by aerobic fermentation of suitable carbon and nitrogen sources in the presence of appropriate nutrients by the organism Pseudomonas elodea, ATCC 31461. Native gellan gum is described in U.S. Pat. No. 4,326,053. The term "gellan gum" includes the native (i.e., non-deacylated), deacylated, partially deacylated, and clarified forms thereof.
Processes for producing gellan gum are also described in U.S. Pat. Nos. 4,326,052; 4,377,636; 4,385,126 and 4,503,084.
When gellan gum is produced via these known processes, the resulting fermentation broth contains large amounts of the bacterial metabolite poly-.beta.-hydroxybutyrate, an intracellular energy storage product. Based on dry weight of the total recovered biomass, PHB is present in amounts of about 15-25%.